Hi,
if your rabbit is old enough to get pregnant it is old enough to handle it. I had a few accidential litters over the years from very young does, none had any problems with it. Might not be optimal, but, except for an emergency spay, there is nothing that can be done about it.
I keep my 4 breeding does in mother-daughter pairs, that works fine for me. There are a few things to consider though. Each of my pairs has 2 hutches, connected with a tunnel. (they also get a lot of garden time). So they can get out of each others eyes when they feel like it, and have privacy, there are times when intact does can be quite bossy and it generally helps with keeping the peace. Also a dividable setting helps when kindling, giving some rest afterwards or for additional feeding of the nursing doe (the other would get fat)
It's actually easier if only one doe is pregnant, I don't seperate for long then, just one or two nights after kindling (they get garden time together), to give her rest and until the feeding got routine. The other doe keeps away from a kindling doe, they seem a little confused about what's going on. Never had a doe messing with the others kits, they become pretty great step moms, I'm pretty sure one even started lactating.
When both does give birth I seperate them when nest building starts (mine do that just a few hours before) or after the first litter is born (there can be several days in between), or at least block off the hutch with the first nest except for feeding times (wildlife camera helps a lot) to prevent the second doe to gather material from the nest or putting her litter in the same nest - which does happen and can work in colony settings, but I'm not too eager to try that. when she's due/starts nest building I confine the doe to the hutch where I want her to nest.
Once the kits become mobile they can wander from one nest to the other, have to keep an eye on that so all get fed (the does don't care which kits they feed, they just want te get rid of the milk), this year I removed a nest since most ended up in the other, and both does just fed that nest.
There's more to check and keeping an eye on, but no big problems.